A copy of the TurboTax tax data file can be opened with the Pro Series. The TurboTax tax data file has a file extension of .taxyyyy, where yyyy is the tax year, eg .tax2021 for tax year 2021
See this TurboTax support FAQ for the tax data file when using the online editions of TurboTax - https://ttlc.intuit.com/turbotax-support/en-us/help-article/import-export-data-files/save-turbotax-online-return-tax-data-file/L4xwOG3LF_US_en_US
See this TurboTax support FAQ for finding the tax data file using the TurboTax desktop editions for Windows - https://ttlc.intuit.com/turbotax-support/en-us/help-article/data-systems/find-tax-data-file-tax-file-windows/L7USQzV4V_US_en_US?uid=lbh1okux
Are you using the Online version?
You can only Transfer from the Desktop program not the Online version. TurboTax Online files can't be transferred directly into ProSeries. They must be saved to the desktop first with a .tax20YY extension. For example .tax2019 for a 2019 TurboTax Online file. I don't know if that means you have to open it in the Desktop program first.
How to Transfer Turbo Tax to ProSeries
https://proconnect.intuit.com/community/convert-data-files/help/how-to-transfer-turbotax-returns-to-proseries/00/6429